Journalistic code of ethics.
"Journalists' main goal is to ensure the right of citizens to truthful and important information, which allows them to form adequate impression about social processes, their essence and importance, about the situation in the modern world."
http://ethicnet.uta.fi/belarus/journalists_ethics_code
Since the printing press this is what's allowed society to shape itself for centuries. The freer information got, the faster change was implemented and the better quality of life got. If the only options most people have for media is controlled by self-invested entities, they're not able to adequately form opinions.